Multifocal Ectopic Purkinje-Related Premature Contractions: A New SCN5A-Related Cardiac Channelopathy.: MEPPC: a new SCN5A-related cardiac channelopathy

International audienceOBJECTIVES: The aim of this study was to describe a new familial cardiac phenotype and to elucidate the electrophysiological mechanism responsible for the disease. BACKGROUND: Mutations in several genes encoding ion channels, especially SCN5A, have emerged as the basis for a variety of inherited cardiac arrhythmias. METHODS: Three unrelated families comprising 21 individuals affected by multifocal ectopic Purkinje-related premature contractions (MEPPC) characterized by narrow junctional and rare sinus beats competing with numerous premature ventricular contractions with right and/or left bundle branch block patterns were identified. RESULTS: Dilated cardiomyopathy was identified in 6 patients, atrial arrhythmias were detected in 9 patients, and sudden death was reported in 5 individuals. Invasive electrophysiological studies demonstrated that premature ventricular complexes originated from the Purkinje tissue. Hydroquinidine treatment dramatically decreased the number of premature ventricular complexes. It normalized the contractile function in 2 patients. All the affected subjects carried the c.665G>A transition in the SCN5A gene. Patch-clamp studies of resulting p.Arg222Gln (R222Q) Nav1.5 revealed a net gain of function of the sodium channel, leading, in silico, to incomplete repolarization in Purkinje cells responsible for premature ventricular action potentials. In vitro and in silico studies recapitulated the normalization of the ventricular action potentials in the presence of quinidine. CONCLUSIONS: A new SCN5A-related cardiac syndrome, MEPPC, was identified. The SCN5A mutation leads to a gain of function of the sodium channel responsible for hyperexcitability of the fascicular-Purkinje system. The MEPPC syndrome is responsive to hydroquinidine

Expression of Phosphoinositide-Specific Phospholipase C Isoforms in Native Endothelial Cells

<div><p>Phospholipase C (PLC) comprises a superfamily of enzymes that play a key role in a wide array of intracellular signalling pathways, including protein kinase C and intracellular calcium. Thirteen different mammalian PLC isoforms have been identified and classified into 6 families (PLC-β, γ, δ, ε, ζ and η) based on their biochemical properties. Although the expression of PLC isoforms is tissue-specific, concomitant expression of different PLC has been reported, suggesting that PLC family is involved in multiple cellular functions. Despite their critical role, the PLC isoforms expressed in native endothelial cells (ECs) remains undetermined. A conventional PCR approach was initially used to elucidate the mRNA expression pattern of PLC isoforms in 3 distinct murine vascular beds: mesenteric (MA), pulmonary (PA) and middle cerebral arteries (MCA). mRNA encoding for most PLC isoforms was detected in MA, MCA and PA with the exception of η2 and β2 (only expressed in PA), δ4 (only expressed in MCA), η1 (expressed in all but MA) and ζ (not detected in any vascular beds tested). The endothelial-specific PLC expression was then sought in freshly isolated ECs. Interestingly, the PLC expression profile appears to differ across the investigated arterial beds. While mRNA for 8 of the 13 PLC isoforms was detected in ECs from MA, two additional PLC isoforms were detected in ECs from PA and MCA. Co-expression of multiple PLC isoforms in ECs suggests an elaborate network of signalling pathways: PLC isoforms may contribute to the complexity or diversity of signalling by their selective localization in cellular microdomains. However in situ immunofluorescence revealed a homogeneous distribution for all PLC isoforms probed (β3, γ2 and δ1) in intact endothelium. Although PLC isoforms play a crucial role in endothelial signal transduction, subcellular localization alone does not appear to be sufficient to determine the role of PLC in the signalling microdomains found in the native endothelium.</p></div

Evaluation of length of stay after transfemoral transcatheter aortic valve implantation with SAPIEN 3 prosthesis A French multicentre prospective observational trial

International audienceBACKGROUND:Complications decrease after transfemoral transcatheter aortic valve implantation (TAVI), and early discharge is feasible and safe in selected populations. AIMS:To evaluate length of stay (LOS) and reasons for prolonged hospitalisation after transfemoral TAVI in unselected patients. METHODS:Patients with severe aortic stenosis, who had transfemoral TAVI with the SAPIEN 3 prosthesis using exclusively local anaesthesia, were prospectively and consecutively included at five French high-volume centres. LOS was calculated from TAVI procedure to discharge. Reasons for prolonged hospitalisation (i.e.>3 days) were evaluated. RESULTS:Between 2017 and 2018, 293 patients were included, with a mean age of 82.4±6.5 years and a mean logistic EuroSCORE of 13.7±9.0%. The in-hospital mortality rate was 1.4%. The median LOS was 5 (3-7) days, and varied considerably between centres (from 2 to 7 days). Sixty-four (21.8%) patients were discharged within 3 days after transfemoral TAVI. Reported reasons for prolonged hospitalisation were complications in 62.2%, loss of autonomy in 3.1%, discharge refusal in 2.2% and logistical reasons in 0.9%. In 31.6% of cases, the investigators reported no apparent reasons. CONCLUSIONS:The results of our study suggest that LOS after transfemoral TAVI, using the SAPIEN 3 prosthesis and a minimalist approach, varies considerably between centres. In almost a third of cases, hospitalisation was prolonged without any apparent reason. Efforts should be made to educate centres to reduce LOS

Summary of mRNA expression for phospholipase C isoforms.

<p><i>MAECs</i>, <i>mesenteric arteries endothelial cells; PAECs</i>, <i>pulmonary arteries endothelial cells; MCAECs</i>, <i>middle cerebral arteries endothelial cells; MA</i>, <i>mesenteric arteries; PA</i>, <i>pulmonary arteries; MCA</i>, <i>middle cerebral arteries</i>.</p><p>Summary of mRNA expression for phospholipase C isoforms.</p

Characterization of phospholipase C ε, ζ and η isoforms in native arteries.

<p><b>A.</b> The presence of mRNA for phospholipase C (PLC) ε, ζ, η1 and η2 isoforms was determined in mesenteric arteries (MA), pulmonary arteries (PA) and middle cerebral arteries (MCA) by PCR. Typical agarose gel electrophoresis of the PCR products showed the expression profile of PLCε, ζ, η1 and η2 isoforms in the different vascular beds and brain or testis were used as control tissue. n = 3. <b>B.</b> Quantitative real time PCR analysis of mRNA expression levels of PLCε, ζ, η1 and η2 isoforms in MA and freshly isolated endothelial cells (ECs) from MA, PA and MCA. Bar graphs show the expression of PLCε (a), ζ (b), η1 (c) and η2 (d) isoforms in MAECs, PAECs, MCAECs, MA and testis as positive control for ζ. n = 3. * P<0.05 between MAECs and MCAECs; # P<0.05 between PAECs and MCAECs; † P<0.05 between MCAECs and MA.</p

Characterization of phospholipase C β isoforms in native arteries.

<p><b>A.</b> The presence of mRNA for phospholipase C (PLC) β isoforms was determined in mesenteric arteries (MA), pulmonary arteries (PA) and middle cerebral arteries (MCA) by PCR. Typical agarose gel electrophoresis of the PCR products showed the expression profile in different vascular beds. Brain and blood were used as positive control tissues. n = 3. <b>B.</b> Quantitative real time PCR analysis of mRNA expression levels of PLCβ isoforms in MA and freshly isolated endothelial cells (ECs) from MA, PA and MCA. Bar graphs show the expression profile of PLCβ1 (a), β2 (b), β3 (c) and β4 (d) isoforms in MAECs, PAECs, MCAECs, MA and blood as control for β2. n = 3. * P<0.05 between MAECs and MCAECs; # P<0.05 between PAECs and MCAECs; † P<0.05 between MCAECs and MAs; ‡ P<0.05 between control tissue and MA. <b>C.</b> (a) Representative immunoblots of murine MA and brain that were obtained using the primary antibody anti-PLC β3 (Abcam #ab52199). GAPDH was used as reference protein. Relevant molecular weight markers are indicated on the left. n = 3. (b) Intracellular distribution of PLCβ3 immunoreactivity in ECs. (Left) Typical image showing labelling of PLC β3 in red and nuclei in blue; scale = 10 μm. (Right) Labelling of PLC β3 (red) overlay with internal elastic lamina (IEL; green) where voids correspond to potential myoendothelial projections; nucleus in blue; scale = 10 μm; n = 4.</p

Characterization of phospholipase C γ isoforms in native arteries.

<p><b>A.</b> The presence or mRNA for phospholipase C (PLC) γ isoforms was determined in mesenteric arteries (MA), pulmonary arteries (PA) and middle cerebral arteries (MCA) by PCR. Typical agarose gel electrophoresis of the PCR products showed the expression profile in the different vascular beds and brain was used as control tissue. n = 3. <b>B.</b> Quantitative real time PCR analysis of mRNA expression levels of PLCγ isoforms in MA and freshly isolated endothelial cells (ECs) from MA, PA and MCA. Bar graphs show the expression profile of PLCγ1 (a) and γ2 (b) isoforms in MAECs, PAECs, MCAECs and MA. n = 3. <b>C.</b> (a) Representative immunoblots of murine MA and brain that were analyzed using the primary antibody anti-PLC γ2 (Abcam #ab18983). GAPDH was used as reference protein. Relevant molecular weight markers are indicated on the left. n = 3. (b) Intracellular distribution of PLCγ2 immunoreactivity in ECs. (Left) Typical image showing labelling of PLCγ2 in red and nuclei in blue; scale = 10 μm. (Right) Labelling of PLCγ2 (red) overlay with internal elastic lamina (IEL; green) where voids correspond to potential myoendothelial projections; nucleus in blue; scale = 10 μm; n = 4.</p

Ezh2 emerges as an epigenetic checkpoint regulator during monocyte differentiation limiting cardiac dysfunction post-MI

Abstract Epigenetic regulation of histone H3K27 methylation has recently emerged as a key step during alternative immunoregulatory M2-like macrophage polarization; known to impact cardiac repair after Myocardial Infarction (MI). We hypothesized that EZH2, responsible for H3K27 methylation, could act as an epigenetic checkpoint regulator during this process. We demonstrate for the first time an ectopic EZH2, and putative, cytoplasmic inactive localization of the epigenetic enzyme, during monocyte differentiation into M2 macrophages in vitro as well as in immunomodulatory cardiac macrophages in vivo in the post-MI acute inflammatory phase. Moreover, we show that pharmacological EZH2 inhibition, with GSK-343, resolves H3K27 methylation of bivalent gene promoters, thus enhancing their expression to promote human monocyte repair functions. In line with this protective effect, GSK-343 treatment accelerated cardiac inflammatory resolution preventing infarct expansion and subsequent cardiac dysfunction in female mice post-MI in vivo. In conclusion, our study reveals that pharmacological epigenetic modulation of cardiac-infiltrating immune cells may hold promise to limit adverse cardiac remodeling after MI